Airtight or waterproof cases are used to enclose cameras and other sensitive apparatus to protect them from their operating environment external thereto which may have moisture, dust, gases and other harmful elements. Cases may suffer from manufacturing defects and may consequently leak.
Detection of leaks in supposedly waterproof casings has been conventionally attempted by detecting the presence of moisture. Schwomma (U.S. Pat. No. 4,312,580) is a representative example. Not only are moisture detectors difficult and expensive to build and maintain, the detection of moisture comes often too late (e.g. moisture has already entered the casing).
As well, detection of leaks has been conventionally attempted by observing changes in the air pressure inside the casing after artificially increasing it. Hayakawa (U.S. Pat. No. 5,305,031) is a representative example. One defect of such attempts is that the means for increasing the air pressure and detecting changes, is itself a potential source of leakage in addition to possible leakage in the cases. For example, after using the Hayakawa device to test the integrity of the cases, it is neither clear that the "self-closing" seal will maintain its integrity nor how to test for that post-testing integrity.